Apparatus for applying coating material



June 12, 1945. N. K. CARLSON APPARATUS FOR APPLYING COATING MATERIAL Filed June 28, 1943 memo/v INVENTOR. NSQL K BY jii a M7 5 1 g/Mm TYZW/YEY? Patented June 12, 1945 APPARATUS FOR AEPPLYING COATING MAT RIAL Neal K. Carlson, Mill Hall, Pm, assignor to The Sherwin-Williams Company. Cleveland, Ohio.

a corporation of Ohio Application June 28, 1943, Serial No. 492.521

2 Claims.

This invention relates to the application of coating material and more particularly to a novel apparatus for use in applying coating material while in a heated condition.

An object of my invention is to provide a novel apparatus for applying heated coating material and in which the congealing of the material in the conduits and spray device or applicator is effectively prevented.

Another object oi this invention is to provide a novel apparatus of the kind mentioned involving the use of an applicator and a heater for the coating material, and in which a continuous circulation of the coating material is maintained between the heater and applicator.

A further object of this invention is to provide a novel apparatus for the application of coating material wherein a stream of the material is delivered through a heater to an applicator so that a portion of the materialflows away from the applicator and wherein such diverted portion is pumped back into said stream at the receiving end oi the heater for repassage therethrough.

The invention may further be briefly summarized as consisting in certain novel combinations and arrangements of parts, hereinafter described in detail and particularly set'out in the appended claims. a

In the accompanying sheet of drawings,

Fig. 1; is an elevational view illustrating my novel apparatus for the application of heated coating material and,

Fig. 2 is-an elevational view showing the applicator or spray device on a larger scale and with portions thereof broken away.

It is desirable to apply certain coating materials. such as lacquer, while in a heated condition and the tendency for such materials to congeal in the applicator and conduits presents a troublesome problem. This tendency to congeal occurs particularly when the coating operation is temporarily interrupted. As will be explained more in detailhereinafter. the present invention overcomes this dimculty by maintaining a-ireeflowing supply of the heated coating material at the applicator at all times.

In the form 01' the apparatus'slmwn in the drawing, I provide a tank l adapted to contain a suppl of lacquer or other fluid coating material of the kind to be applied while hot. and an applicator II to which the coating material is supplied for application to a desired surface or artlcle. A heater I2 located between the tank and applicator heats the material being supplied to the latter.

' circulating material as close to the applicator ii The supply tank or reservoir I0 is provided with a cover I! by which it can be closed and sealed so that a pressure condition can be maintained in the tank for discharging the coating material therefrom through the delivery conduit or pipe I. The pressure condition can be created in the tank Ill by supplying compressed air thereto through the pipe I! and the hose Isa. The air connection to the tank is preferably made through the cover l3 and may include suitable pressure regulating valves i8 and pressure gauges i1.- This air connection may also include a shut-oil valve i8 and a relief cock l8a.

The applicator I i is here shown as being a mechanical or atomizing applicator of the kind known as a spray gun. This device includes a handle H by which it can be held and manipulated. and a nozzle 20 from which atomized coating material is discharged. .The delivery of the atomized coating material is controlled by the lever or trigger 2i. Compressed air for the atomization of the coating material is supplied to the applicator through the hose or conduit 22. The heated coating material is supplied to the applicator through the hose or conduit 23.

The heater l2 may be or the kind comprising an insulated shell 25 forming a container for a quantity of the coating material to be heated. and

to the coil 26 through a pipe 32 leading from the steam line 33 and the condensate may be dis charged from the coil 28 through the exhaust connection 34 and the steam trap 35.

As already stated in a general way, I prevent the congealing of the coating material by maintaining a free-flowing supply of the heated material at the-applicator ii at all times and. to this end, I maintain a continuous circulation of the coatins material between the heater i2 and the applicator. For this purpose I provide a return con-- duit 38 as a branch or continuation of the conduit 23 and which carries coating material away from the applicator. It is desirable to bring the as practical and this is accomplished by connecting the conduits 23 and 18 with the receiving nipple 81 01 the applicator by means of the Y-ntting 88.-

' The oating material which is diverted or returned from the applicator H by the conduit 36 is forced back into the main passage or stream of coating material at or adjacent the receiving A shut-off valve 48 may also be provided in thepipe 44 ahead of the needle valve it.

The compressed air supply for the tank Hi, the applicator II, and the air motor 43, may be obtained from the main air line 41. These devices maybe supplied directly from the line 41 but are preferably connected therewith through a separator 48 which serves to remove water and sediment from the compressed air being supplied.

In my novel apparatus, the coating material in the tank I is discharged therefrom by the pressure in the tank and is forced through the heater i! to the Y-fltting 88 at the applicator II. The pressure in the tank should be such that heated coating material can be supplied to the Y-fitting 38 at a rate in excess of the maximum rate of discharge from the nozzle 20. If the applicator is being used, some of the heated material is discharged or sprayed from the nozzle and the remainder or excess returns through the line 38 to the intake of the pump 40. The operation oi. the pump should be such that it increases or boosts the pressure of the coating material somewhat above the pressure in the main stream in the piping l4 and forces the diverted material back into such main stream for repassage through the heater [2. If the applicator l I is idle, all of the heated material being supplied through the conduit 23 is returned or withdrawn through the conduit 36 and is forced by the pump back into the main fluid passage at the receiving end of the heater. Thus the pump 49 will maintain a continuous circulation of coating material between the heater and applicator regardles of whether the applicator is being used or is idle, and hence, this pump can be referred to as a recirculating pump.

Although the drawing shows but one applicator i i, it is obvious that a number of such applicators can be connected with and served by the heater I2 and the pump 40.

From the foregoing description and accompanying drawing it will now be readily understood that I have provided a novel apparatus for applying coating material in a heated condition, and wherein the congealing of the material in the applicator and conduits is effectively prevented. It will also be seen that a continuous circulation oi the coatingmaterial is maintained between the applicator and heaterso that a supply'of free-flowing coating material at the desired temperature will always be available at the applicator and even though the applicator is temporarily idle, there will be little or no tendency for the coating material to congeal.

While I have illustrated and described my novel coating apparatus in considerable detail, it should be understood that I do not intend my invention to be correspondingly limited but reard the same asincluding all changes and modiiications coming within the scope of the appended claims.

Having thus describedmy invention, I claim:

1. In a system of the character described, a spray gun oi! the kind adapted to utilize anpressure for atomizing fluid spray material, a tank adapted to contain a quantity of said fluid spray material, a supply connection from said tank to said gun for supplying spray material to the latter, a heater between said tank and gun and adapted to heat the material being supplied to the latter, said tank being a closed tank adapted to be supplied with air under pressure sufllcient for delivering spray material therefrom to the spray gun through said supply connection and heater in a quantity in excess of that required by the spray gun when the latter is being operated, means connected with said tank for supplying said air under pressure thereto, means for supplying air under pressure to said spray gun for use in atomizing said spray material, and a recirculating pump having its intake communicating with said supply connection at a point adjacent said gun and its discharge communicating with said supply connection on the tank-side of said heater. said pump being operable to cause spray material to be returned from said gun to said supply connection at a point adjacent the inlet end of the heater so that a quantity oi the spray material will be circulated continuously between the heater and gun during both the operative and inoperative condition of the gun.

2. In a system of the character described, a spray gun of the kind adapted to utilize air under pressure for atomizing fluid spray material, a tank adapted to contain a quantity of said fluid spray material, a heater for said material having its receiving end connected with said tank and its delivery and connected with said gun, said tank being closed and adapted to be supplied with air under pressure sufficient for delivering therefrom a stream of spray material to the gun through said heater under an initial pressure and in a volume in excess of that required by the gun when the latter is being operated, means connected with said tank for supplying said air under pressure thereto, means for supplying said air under pressure to the spray gun for use in atomizing said spray material, and a recirculating pump having its intake communicating with the delivery connection of the heater at a point closely adjacent said gun and its discharge connected with the receiving end of the heater, said pump being operable to withdraw a portion of the material being supplied to the gun and to increase the pressure of the withdrawn material above said initial pressure and to discharge the withdrawn material into said stream adjacent the receiving end of the heater.

NEAL K. CARLSON. 

